Process of cooling concrete



UNlTED STATES PATENT OFFICE PROCESS OF COOLING CONCRETE Heinrich Pahl, Wiesbaden, Germany, assignor to Gesellschaft fiir Lindes Eismaschinen A. G., Wiesbaden, Germany, a corporation of Germany No Drawing.

Application July 29, 1939, Serial No. 287,407. In Germany August 11, 1938 2 Claims.

As is well known heat is liberated in the setting of concrete. As a result the temperature of the concrete mass may rise so high that the structure will be damaged unless steps are taken to dissipate the heat and limit the rise in temperature. In the case of relatively small structures contact with the surrounding cool air or water sprayed on to the structure may be sufilcient to prevent the development of a harmful temperature. In large structures, however, in which there are large masses, for instance, in dam construction, natural cooling or cooling by spraying the surface of the structure is not suflicient to prevent the development of harmful high temperatures within the structure.

It has been proposed to cool such massive concrete structures by embedding pipes in the structure and passing a cooling liquid through the pipes but this expedient involves the drawbacks that the pipes are expensive and cannot be recovered and must, after they have served their purpose for cooling, be carefully filled with concrete.

It has also been proposed to cool the constituents of the concrete before the mixing but this is objectionable because the inefificiency of heat transfer between cooling surfaces or media and the concrete constituents make necessary the use of large and expensive apparatus. The same objection applies to the proposal to cool the concrete mixture.

It has now been found that a sufficient cooling of the concrete mixture may be secured by supplying to the concrete mixture, during the mixing operation, a portion of the necessary water in the form of ice. This was surprising because it was not anticipated that the relatively small amount of water required for the mixing of concrete, in the form of ice, would supply sufiicient cold to produce the desired low temperature, near 0 C., in the mixture or that this amount of cold would adequately neutralize the heat of setting of the concrete.

In accordance with the present invention of a harmful high temperature in the concrete structure. It is preferred to supply the ice to the mixing operation in finely divided form so that the cooling of the other constituents will be rapid and the ice will be melted to water during the normal mixing period. The water which must be frozen to ice amounts to only a small proportion of the concrete mixture and the cost of freezing it is relatively small and inexpensive compared to the cost of cooling the other constituents of the concrete mixture by contact with cold air or cold surfaces as heretofore proposed. Damage to the concrete due to cooling to too low a temperature is easily avoided because it is a simple matter to determine the quantity of ice required to bring the temperature of the mixture to the desired point. Even when the mixture is cooled to near 0 C. it soon attains a higher temperature due to the liberation of the setting heat within the mass.

I claim:

1. In the production of concrete structures the steps which consist in adding in the form of ice to the other constituents of a concrete mixture at a higher temperature so much of the water normally required for said concrete mixture as upon complete melting will lower the temperature of the resulting concrete mixture to near 0 C., mixing said constituents and ice until the ice has melted completely, and placing the resulting mixture.

2. Process as defined in claim 1 in which the ice is introduced in finely divided form into the concrete mixture during the customary mixing operation.

HEINRICH PAHI. 

